A spherical red or purple gall which forms on the leaves or male catkins of oak trees in response to the developing larva of a gall wasp. It results from eggs laid in the spring and alternates within the annual cycle with the spangle gall

A reddish disc-shaped gall that forms on the undersides of oak leaves in response to the developing larva of a gall wasp. It results from eggs laid in the summer and alternates with the currant gall within the annual cycle